Research has recently been undertaken on the possibility that magnetic fields may cause cancer, reproductive abnormalities, or psychoneurological disorders [Bierbaum and Peters, 1991]. Research emphasis is being placed on possible effects of magnetic fields produced by AC electric power transmission facilities and electric appliances, although other sources may be involved. In order to carry out such research more effectively and accurately, there is a requirement for instrumentation for measuring magnetic fields with frequencies below 3000 Hz. Moreover, it is necessary to make such measurements in workplaces, homes and other environments so that compact, transportable, instruments are required.
Although many instruments are available for measuring magnetic fields in the environment, such instruments do not distinguish between those magnetic fields which may interact with a biological organism and those which may not. Thus, in order to obtain meaningful research results, it is necessary to be able to identify and measure magnetic fields which may have biological effects on the human body.
To explain the biological effects of interest, it has been proposed that ions important to cell functioning may experience "cyclotron resonance" [Liboff et al., 1990] or "parametric resonance" [Lednev, 1991]. Other forms of magnetic resonance with the magnetic fields in the environment are being investigated for potential chemical effects produced thereby [Grundler, et al., 1992]. For example, electron spin resonance is known to enhance the production of "free radical" molecules [Steiner and Ulrich, 1989; McLaughlin, 1992], and magnetic field interactions with magnetosomes (biological magnetic crystals) are being studied [Kirschvink, 1992].
The magnetic field combinations that cause nuclear magnetic resonance and electron spin resonance are well known [Macomber, 1976], and laboratory studies now suggest that magnetic resonance principles may apply to magnetic moments from electron spin, ferromagnetic crystals, or ionic motion in biological substrates. These hypotheses imply that biological processes can be affected by combinations of oscillating and static magnetic fields which are in resonance with magnetic moments in the human body.
In order to determine resonance conditions, it is necessary to measure both static and oscillating magnetic fields, and to provide output data more detailed than an average magnitude of either (or both) the static and oscillating fields. It is also necessary to identify the frequency components of the oscillating field as well as the relative spatial orientation of the two fields.
More specifically, it is necessary to monitor all the temporal, spatial and frequency characteristics of a magnetic field which may have biological effects on the human body.
It is moreover necessary to analyze the measured magnetic field characteristics in order to provide a quantity indicative of such resonance. It is particularly desirable to measure and identify magnetic field components capable of resonance with a predetermined magnetic moment, such as a magnetic moment indicative of biological resonance and more specifically indicative of resonance with the human body. Preferably, such measurement, analysis and identification should be performed in accordance with known theories of magnetic resonance.
Indeed, in some laboratory experiments [Blackman, 1990; Liboff et al., 1990], biological changes attributed to magnetic fields have been found to depend on a relation between the frequency and orientation of a oscillating field produced by AC electricity and a static magnetic field originating in the earth (the geomagnetic field).
To determine a linkage or causal relationship between magnetic resonances and cancer, spontaneous abortions or other health disorders associated with magnetic fields in epidemiological studies, instruments are thus needed to measure and monitor magnetic resonance conditions in the environment. Such instruments would be used in epidemiological studies to measure exposures to magnetic resonances of subjects in their homes, workplaces and other environments.
Moreover, if it is established that exposure to magnetic resonances is a risk factor for diseases, then magnetic resonance monitors will also be required to measure exposure to resonance conditions in order to evaluate health risks and control devices thereof.
The present invention is thus provided to permit measurement of magnetic field combinations which are, or may be, in resonance with magnetic moments in a biological organism, such as the human body.
Many systems are known for measuring exposures to magnetic fields with extremely low frequencies. However, the known systems are not suited for measuring human exposures to magnetic resonance conditions in health studies. The deficiencies of the prior art are based on the following.
1. Many systems only measure a oscillating magnetic field in frequency bandwidths which include the electric power frequency (60 Hz in North America and 50 Hz in the rest of the world). Frequencies from 30-3000 Hz is called the extremely low frequency (ELF) range. The most common sensor for measuring ELF magnetic fields is an induction coil, which responds to the oscillating fields but not to the static fields also needed for consideration in determining resonance conditions. Such common sensor systems are available from various sources, such as AJM Electronics, Electric Field Measurements, Enertech Consultants, Holaday Industries, and Positron Industries. PA1 2. Most systems which measure both static and oscillating magnetic fields use either Hall-effect probes or flux-gate probes. Such systems are also limited, and can only determine the average magnitude of the field's component, either static or ELF. These instruments often label these two frequency modes as the "DC" and "AC" modes. Such systems are available from companies such as Bartington Instruments, F. W. Bell, Holaday Industries, and Schoenstedt Instrument Company. The magnetic field instruments with an ELF output usually determine the root-mean-squared (rms) magnitude of that field component through a frequency filter with a fixed bandwidth. Since resonance occurs at specific frequencies which vary with the magnitude of the static magnetic field, however, resonance conditions cannot be determined from the rms magnitudes measured through a pre-set frequency filter. PA1 3. Some systems measure the frequency spectrum of the ELF magnetic fields. Such systems are available from Electric Field Measurements, Inc. and Innovatum, Inc. However, these systems do not measure the static magnetic field or the spatial orientation of the ELF magnetic field. PA1 4. Systems which measure the spatial orientation and frequency spectrum of the static and oscillating magnetic fields simultaneously are available from Electric Research and Management, Inc. However, these systems do not analyze the signal in accordance with theories of magnetic resonance.
It is noted that the systems described at paragraph (4) measure all the physical characteristics of the static and oscillating magnetic fields, with no consideration given to any potential chemical and biological effects thereof. Consequently, these instruments are large, heavy, expensive, and demanding to operate. Interpreting the measurement results thereof requires extensive computer analysis, which is ordinarily done at a location remote from the environment where the measurements were taken.
Therefore, such systems are strictly instruments for gathering research data, unsuited for the efficient measurement and evaluation of occupational and environmental health risks from magnetic resonance conditions.